hibernate annotation 之 一对多、多对一双向外键关联
假设，一个农场产出多种植物，具体的某一植物产于某一农场。
1 package net.yeah.fancydeepin.po;
2
3 import java.io.Serializable;
4 import java.util.Set;
5 import javax.persistence.CascadeType;
6 import javax.persistence.Column;
7 import javax.persistence.Entity;
8 import javax.persistence.FetchType;
9 import javax.persistence.GeneratedValue;
10 import javax.persistence.Id;
11 import javax.persistence.OneToMany;
12 /**
13 * -----------------------------------------
14 * @描述 农场
15 * @作者 fancy
16 * @邮箱 fancydeepin@yeah.net
17 * @日期 2012-10-21 <p>
18 * -----------------------------------------
19 */
20 @Entity
21 public class Farm implements Serializable{
22
23 private static final long serialVersionUID = 1L;
24
25 private Integer id;
26 private String name;
27 private Set<Plant> plantSet;
28
29 @Id
30 @GeneratedValue
31 public Integer getId() {
32 return id;
33 }
34 @Column(length = 18, nullable = false)
35 public String getName() {
36 return name;
37 }
38 @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "farm")
39 public Set<Plant> getPlantSet() {
40 return plantSet;
41 }
42 public void setId(Integer id) {
43 this.id = id;
44 }
45 public void setName(String name) {
46 this.name = name;
47 }
48 public void setPlantSet(Set<Plant> plantSet) {
49 this.plantSet = plantSet;
50 }
51 }
1 package net.yeah.fancydeepin.po;
2
3 import java.io.Serializable;
4 import javax.persistence.CascadeType;
5 import javax.persistence.Column;
6 import javax.persistence.Entity;
7 import javax.persistence.FetchType;
8 import javax.persistence.GeneratedValue;
9 import javax.persistence.Id;
10 import javax.persistence.ManyToOne;
11 /**
12 * -----------------------------------------
13 * @描述 植物
14 * @作者 fancy
15 * @邮箱 fancydeepin@yeah.net
16 * @日期 2012-10-21 <p>
17 * -----------------------------------------
18 */
19 @Entity
20 public class Plant implements Serializable{
21
22 private static final long serialVersionUID = 1L;
23
24 private Integer id;
25 private String name;
26 private Farm farm;
27
28 @Id
29 @GeneratedValue
30 public Integer getId() {
31 return id;
32 }
33 @Column(length = 18, nullable = false)
34 public String getName() {
35 return name;
36 }
37 @ManyToOne(cascade = CascadeType.PERSIST, optional = false, fetch = FetchType.LAZY)
38 public Farm getFarm() {
39 return farm;
40 }
41 public void setId(Integer id) {
42 this.id = id;
43 }
44 public void setName(String name) {
45 this.name = name;
46 }
47 public void setFarm(Farm farm) {
48 this.farm = farm;
49 }
50
51 }
Junit 测试 :
1 @Test
2 public void createTable(){
3
4 new SchemaExport(new AnnotationConfiguration().configure()).create(true, true);
5 }
执行上面的单元测试，数据库中生成的表的结构图 :
级联保存 :
1 @BeforeClass
2 public static void beforeClass(){
3
4 session = new AnnotationConfiguration().configure().buildSessionFactory().getCurrentSession();
5 }
6
7 @Test
8 public void insert(){
9 try {
10 Farm farm = new Farm();
11 farm.setName("fancy-farm");
12 Plant tomato = new Plant();
13 tomato.setName("番茄");
14 tomato.setFarm(farm);
15 Plant cabbage = new Plant();
16 cabbage.setName("卷心菜");
17 cabbage.setFarm(farm);
18 Set<Plant> plantSet = new HashSet<Plant>();
19 plantSet.add(tomato);
20 plantSet.add(cabbage);
21 farm.setPlantSet(plantSet);
22 session.beginTransaction();
23 session.persist(farm);
24 session.getTransaction().commit();
25 } catch (Exception e) {
26 &
补充：软件开发 , Java ,
